Two Finger Knuckle Duster DFK 01 Aerospace Aluminum

Dimensions:
Material - Aerospace Aluminum
Finish - Polished
Height - 2 11/64’’ (55 mm) 
Width - 2 13/32’’ (61 mm) 
Thickness - 43/64" (17 mm) 
Finger hole diameter - 1" (25 mm)
Weight - 3 oz / 90 grams

More similar products you can find here:
price for real aerospace aluminum brass knuckles in the USA

Special holes allow you to use this product as a Keychain. 
You can also thread a paracord (550-type) lanyard through the holes.
Nice gift for Her.

EDCCraftStore official website is the best place to buy original EDC-products at manufacturer's price.